1. Field of the Invention
This invention relates to an apparatus for attaching handles to containers. Particularly, this invention relates to an apparatus for attaching plastic handles to plastic containers. More particularly, this invention relates to an apparatus for attaching inconsistently sized and shaped plastic handles to plastic containers.
The invention is particularly applicable to plastic pails having plastic handles which are subjected to loads or forces below freezing temperatures, and will be described with particular reference thereto. However, it will be appreciated that the invention is broader and more general in application, and may be advantageously employed with other containers.
2. Description of The Art
An injection molded plastic container of the type generally used to package food products, is a one-piece or unitary cylindrical container. Usually, a container is formed such that it is closed at the bottom end with a tapered circumferentially continuous sidewall chamber extending from the closed bottom end to an upper open end. The upper end of each container includes a lip and a rim that lockingly cooperate with a separately formed closure member or lid. The lid, likewise, includes a lip portion adapted to snap fit and securely lock over the rim to close the container.
Also provided adjacent the upper edge of each container are a pair of bail ears to engage a bail or handle. Preferably, the bail ears are integrally molded of the same plastic as the remainder of the container, for example, recyclable high density polyethylene. The bail ears extend radially outward from the container sidewall and are disposed diametrically opposite one another to provide balance when the container is carried by the bail. Each ear may include a mounting face spaced outwardly from the remainder of the container sidewall, having an aperture extending therethrough adapted to receive opposed ends of the bail. Often, commercially available containers use a bail formed from metal wire stock.
Although containers of this general type have met with commercial success, the metal bail, although still the most commonly used type of bail, is not preferred for all situations. There are some problems associated with its use. For example, there is potential for puncturing the plastic container, particularly when the container is exposed to subfreezing temperatures. During the packaging and distribution process at subfreezing temperatures, plastic has a greater chance of breaking because it is brittle at low temperatures. If impact occurs, the metal handle may be driven through the brittle plastic and may break away a piece of the plastic into the contents of the package. In the case of food products, the risk of a plastic piece being dislodged into the food product is undesirable. This problem is generally known in the industry as "coining".
Another problem associated with a metal bail is a potential for interference with a metal detector installed in a food-processing plant used to monitor the contents of the food product in a container. The metal detector determines the presence of undesirable metal, inadvertently intermixed with the food product. As is apparent, the metal bail could falsely trigger the metal detector. Accordingly, the use of a plastic handle to provide a completely plastic container is desirable.
Another area of increasing concern is the ability to recycle containers. As with so many other products, the limited space remaining in landfills has brought an increased focus on the ability to recycle. Although the plastic container is itself recyclable, and metal bails are recyclable, combined plastic and metal products are undesirable since it is considered a commingled product. Additional handling and expense must be encountered at the recycling facility to separate different material components. Accordingly, recycling demands also make a plastic handle preferable.
Details of a preferred completely plastic container and handle may be found in commonly assigned U.S. Pat. Nos. 4,997,098, and U.S. Ser. No. 911,517 filed Jul. 10, 1992. The disclosure of each is hereby incorporated by reference.
U.S. Ser. No. 911,517 describes the advantages of plastic handles and provides an acceptable plastic handle design. However, processes for making plastic handles are such that tolerances are generally quite broad. This occurs primarily due to large and unpredictable shrinkage in molded polyethylene. There is often a variation in length from one handle to another of up to one half inch. Furthermore, the elevated temperature of the molding process provides ample thermal energy to the handles to allow warping or bowing after removal from the mold. Accordingly, traditional mechanisms for mounting the bail or handle are not satisfactory.
U.S. Pat. No. 3,626,879 describes a process for attaching plastic bails, wherein the bail must be cut or punched to a predetermined length to be useful. The additional step of cutting and punching molded handles is required due to their inconsistent length. Specifically, in the process described in the U.S. Pat. No. 3,626,879, a bail handle having a non-standard distance between the holes in the handle would result in misalignment of the button-like protuberances with the apertures of the bail. This may result in the failure of one end of the bail to interlock with its corresponding bail ear. If one hole and ear do interlock, tearing of either the bail or the ear receptacle may occur. Accordingly, U.S. Pat. No. 3,626,879 does not address the difficulty encountered in the attachment of bails having protuberances separated by inconsistent distances.
U.S. Pat. No. 4,236,305 shows a means for mounting a plastic handle via a resilient ring; however, it does not address the issue of inconsistent bail length.
For these reasons, molded polyethylene handles have traditionally been applied to containers by hand. Therefore, this particular art is in need of an apparatus for attaching bowed handles or handles of inconsistent lengths to a container.